I agree with @ChazMaz.
I can’t see any economic or efficiency benefits for changing both headlight bulbs at once. Replacing two separate bulbs is still two jobs, and the only labour saved by doing both in one go is that you open and close the bonnet just once, which I don’t consider to be very much effort at all. I don’t think it’s that sensible to change both bulbs at once on the assumption that their lifespan will be about the same either – I don’t think lightbulbs are that predictable, and bulb lifespan can vary a lot. As inexpensive as bulbs may be where you live (they are a rip off here!), I’d consider it a bit wasteful to discard a perfectly functioning bulb.
Tyres are a different matter entirely. The wear on tyres on the nearside and offside of each axel should match, so that you have the same level of grip for the tyres on each side of the axel. If you change just one so you have a new tyre and a worn tyre, the wear of the tread for the tyres on that particular axel will be uneven. The handling of your car will be altered when driving normally, and in the event of an accident, you’ll be far less likely to skid in an even straight line. Therefore, you should change tyres in pairs, and ideally, change the lot in one go.